Halo-Shaped Flowing Atmospheric Pressure Afterglow: A Heavenly Design for Simplified Sample Introduction and Improved Ionization in Ambient Mass Spectrometry

Halo-Shaped Flowing Atmospheric Pressure Afterglow: A Heavenly Design for Simplified Sample Introduction and Improved Ionization in Ambient Mass Spectrometry

The flowing atmospheric-pressure afterglow (FAPA) is a promising new source for atmospheric-pressure, ambient desorption/ionization mass spectrometry. However, problems exist with reproducible sample introduction into the FAPA source. To overcome this limitation, a new FAPA geometry has been develop...

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Bibliographic Details
Published in:Analytical chemistry (Washington) 2013-08, Vol.85 (15), p.7512-7518
Main Authors: Pfeuffer, Kevin P, Schaper, J. Niklas, Shelley, Jacob T, Ray, Steven J, Chan, George C.-Y, Bings, Nicolas H, Hieftje, Gary M
Format: Article
Language:eng
Subjects:
Aerosols
Afterglows
Atmospheric Pressure
Channels
Desorption
Discharge
Electric Conductivity
Electrodes
Equipment Design
Fluid dynamics
Geometry
Ionization
Ions
Mass spectrometry
Mass Spectrometry - instrumentation
Pharmaceutical Preparations - chemistry
Sampling
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Summary:The flowing atmospheric-pressure afterglow (FAPA) is a promising new source for atmospheric-pressure, ambient desorption/ionization mass spectrometry. However, problems exist with reproducible sample introduction into the FAPA source. To overcome this limitation, a new FAPA geometry has been developed in which concentric tubular electrodes are utilized to form a halo-shaped discharge; this geometry has been termed the halo-FAPA or h-FAPA. With this new geometry, it is still possible to achieve direct desorption and ionization from a surface; however, sample introduction through the inner capillary is also possible and improves interaction between the sample material (solution, vapor, or aerosol) and the plasma to promote desorption and ionization. The h-FAPA operates with a helium gas flow of 0.60 L/min outer, 0.30 L/min inner, and applied current of 30 mA at 200 V for 6 W of power. In addition, separation of the discharge proper and sample material prevents perturbations to the plasma. Optical-emission characterization and gas rotational temperatures reveal that the temperature of the discharge is not significantly affected (
ISSN:0003-2700
1520-6882